Reports of Bovine Tuberculosis (TB) in livestock from Northeast England’s County Durham have local farmers worried that infections could spread to more areas. The herd suspected of spreading infection tested positive for the illness on November 11 from a farm near Haswell. In response to concerns of widespread infection of valuable livestock, the Animal Health and Veterinary Laboratories Agency (AHVLA) announced that TB testing is taking place in all farms near and surrounding the center of outbreak. Animals testing positive have been placed under movement restrictions or removed for slaughtering. This is the first incident of bovine TB in the county for some time now as strict regulations to control the spread of disease have been put into action. The U.K. government has identified three bovine TB risk areas: high-risk area, edge area, and low-risk area. Regulations currently in place aim to prevent diseased livestock from high-risk areas in the south-west and west midlands from being transported to farms in low-risk areas. Other measures of preventing Bovine TB such as killing over 1500 badgers suspected in helping to spread the disease have been very controversial.
Bovine tuberculosis is a chronic bacterial disease caused from infection by the Mycobacterium bovis bacterium that affects cattle and sometimes other mammals, such as elk or deer. Bovine TB can be spread through inhalation or ingestion of infective material as well as through breaks in the skin. Tuberculosis can be a debilitating disease in cattle, causing clinical signs such as low fever, dehydration, diarrhea, and weight loss. More severe symptoms include acute respiratory distress and enlarged lymph nodes. Early infections and more mild cases of the disease may be asymptomatic and more difficult to diagnose without further skin tests. The majority of the United States is declared free of bovine TB, and more than one million animals are reportedly tested for the disease each year. However, the disease has been known to spread through other infected animals such as deer and badgers, a particular problem in parts of England. The Center for Food Security and Public Health at Iowa State University recommends that farmers suspecting bovine TB in their livestock isolate possibly affected animals and monitor the health of other cattle. Affected herds should be tested periodically and all positively tested animals should be slaughtered to prevent further infection.
Although bovine tuberculosis caused by the Mycobacterium bovis bacterium can affect humans as well, in the United States, the majority of tuberculosis cases in people are due to infection by Mycobacterium tuberculosis. The United Kingdom’s Public Health England website states that while in 1941 six percent of all deaths from tuberculosis were due to the bovine strain, current risk of human infection is negligible. Data collected between 2000 and 2012 also shows that those over the age of 65 account for 57 percent of human bovine tuberculosis cases. Public health authorities suggest that the majority of cases in the UK are due to reactivated latent infections that were probably acquired before more controls over milk pasteurization and slaughtering controls were implemented. According to the Centers for Disease Control and Prevention (CDC), those that do contract bovine tuberculosis are more likely infected by the bacteria by eating or drinking contaminated or unpasteurized dairy products. Pasteurization, which rapidly heats and cools dairy products to kill bacteria, is one important measure taken to prevent the spread of this disease in humans.
The CDC also states that those in close contact with possibly infected livestock such as dairy farmers, ranchers, or butchers are at higher risk of being infected with bovine tuberculosis. Although caused by a different bacterium, symptoms of bovine tuberculosis infection in humans are the same as other TB infections and include night sweats, fever, weight loss, persistent cough, or abdominal pain. Like M. tuberculosis, bovine TB in humans is treated with a combination of antibiotics. Treatment in cattle however, according to the OIE, is “rarely attempted because of the high cost, lengthy time and the larger goal of eliminated the disease.”
Sources:
Centers for Disease Control and Prevention. Mycobacterium bovis (Bovine Tuberculosis) in Humans . Atlanta: , Web. <http://www.cdc.gov/tb/publications/factsheets/general/mbovis.pdf>.
OIE. Bovine tuberculosis Web. http://www.oie.int/fileadmin/Home/eng/Media_Center/docs/pdf/Disease_cards/BOVINE-TB-EN.pdf.
Tasker, John. " Cattle movements blamed for Durham TB outbreak."Farmers Weekly 12 11 2013, n. pag. Web. 13 Nov. 2013. <http://www.fwi.co.uk/articles/12/11/2013/141941/cattle-movements-blamed-for-durham-tb-outbreak.htm>.
The Center for Food Safety and Public Health. Bovine Tuberculosis. Web. <http://www.cfsph.iastate.edu/Factsheets/pdfs/bovine_tuberculosis.pdf>.
Willis, Joe. "Bovine TB case confirmed in County Durham." Northern Echo 09 11 2013, n. pag. Web. 13 Nov. 2013. <http://www.thenorthernecho.co.uk/NEWS/10797783.Bovine_TB_outbreak_confirmed_in_County_Durham/>.
